Citigroup Inc. said it had identified "methodological issues" with how it determined annual percentage rates for certain credit card customers.

The New York-based banking company, among the largest card issuers in the country, said in its Form 10-K filed Feb. 23 that it would provide "remediation" to affected customers.

Citi said in the annual SEC filing that it self-reported the card problems to its regulators and that it is "cooperating fully with the regulatory reviews." The bank did not disclose how many customers were affected nor how much money was involved.

The company said the issues were tied to provisions of the Credit Card Accountability Responsibility and Disclosure Act and Regulation Z.